Abstract
In following changes in bone density in individuals, a densitometrist is generally interested in disease progression or therapeutic efficacy. As densitometry has become more widespread, the awareness of the number of diseases with effects on skeletal density has also increased. Nevertheless, monitoring changes in bone density is still primarily done to assess therapeutic efficacy of bone active agents. An increase in bone density, or, depending on the agent, stabilization of the bone density is considered an appropriate surrogate for efficacy of the agent in reducing fracture risk. Although effects on bone density are not the only means by which therapeutic agents may reduce fracture risk, meta-analyses of the relationship between changes in bone density and spine fracture risk have consistently demonstrated a statistically significant relationship between increasing bone density and declining spine fracture risk (1, 2). The same can be said of non-spine fractures and bone density, in which the relationship appears to be even stronger (3). This does not negate any potential effects of therapeutic agents on non-density factors in reducing fracture risk. It simply means that changes in bone density remain the best surrogate marker for fracture risk reduction in clinical practice. To properly follow changes in bone density and interpret the results, the densitometrist must be thoroughly familiar with the concept of precision, which was introduced in Chapter 3.
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Notes
- 1.
Although the name of the organization is the International Organization for Standardization, it is generally known as ISO and not IOS.
- 2.
The Gaussian distribution is discussed in Chapter 3.
- 3.
Although the RMS-SD is preferred to the RMS-%CV, the change in bone density from baseline seen with various therapeutic agents is generally given as a percentage in the medical literature, necessitating the use of the RMS-%CV for the calculation of the time to the LSC.
- 4.
At http://www.iscd.org an Excel spreadsheet is available at no cost for download by ISCD members that allows the physician to enter the bone density values obtained during a precision study. The precision is calculated automatically by formulas imbedded in the spreadsheet. The spreadsheet can only be used with Microsoft® Excel.
- 5.
See Chapter 6 for a discussion of BMD data obtained different devices from the same manufacturer.
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Bonnick, S.L. (2010). Monitoring Changes in Bone Density. In: Bone Densitometry in Clinical Practice. Current Clinical Practice. Humana Press, Totowa, NJ. https://doi.org/10.1007/978-1-60327-499-9_11
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